1. Field of the Invention
The present invention relates generally to a controlling apparatus for an active suspension system for an automotive vehicle and more particularly to an apparatus for controlling the active suspension system, wherein a control logic is incorporated in a controller for the suspension system.
2. Description of the Related Art
A conventional active suspension system for an automotive vehicle using pneumatic springs of the type including a vertical acceleration sensor for detecting a vertical acceleration above the springs for each of front/left, front/right, rear/left and rear/right air suspensions, respectively, a suspension stroke sensor for detecting a vertical relative displacement quantity above and below the spring for each air suspension, a controller for obtaining by calculating an instruction air flow quantity to be fed to each air suspension and to be discharged from each air suspension based on the vertical acceleration above the spring detected by the vertical acceleration sensor, the vertical relative displacement quantity detected by the suspension stroke sensor and a vertical relative displacement speed obtained from the vertical relative displacement quantity by calculation and a flow rate control valve for performing air feeding or air discharging in accordance with the instruction flow quantities independently per each air suspension whereby controlling is accomplished independently per each air suspension so as to vary an apparent mass of the vehicle body, a damper effect and a spring effect has been developed by a common applicant to the applicant of the present patent application and it was already laid open under Japanese Laid-Open Patent No. 139,709/1987.
Since the conventional active suspension is controlled by feeding and/or discharging air in the air suspension according to a vertical acceleration of the mass above the spring, and a relative displacement and a relative displacement speed between the masses above and below the spring, it is very effective to satisfy a soft feeling performance when receiving a sudden upward impulse from roads. And it is also very effective to keep the vehicle in proper attitude when receiving a slow moving force from roads.
However, the conventional active suspension system has a problem that when a large magnitude of longitudinal acceleration induced by quick braking, or a large magnitude of transverse acceleration induced by quick turning movement is exerted on the vehicle body, a certain delay for controlling to feed or discharge air tends to occur in response to quick movement of the load due to the aforementioned accelerations.
The present invention has been made with the foregoing problem in mind.